Kinematics of Herbig-Haro Objects and Jets in the Orion Nebula

Abstract

We have surveyed the inner 5' of the Orion Nebula by means of Hα and [N II] Fabry-Perot imaging spectroscopy to present a kinematical study of the Herbig-Haro objects in the nebula. The objects studied in this work are HH 202, 203, 204, 529, 269, and other associated features. For HH 202 we find new features that, because of their high velocities (up to 100 km s-1), indicate the presence of an outflow that probably is an HH flow not cataloged previously. HH 202 could be only a part of this larger outflow. Large internal motions are found in the fainter regions of HH 203-204, as well as evidence of transverse density gradients that could account for the asymmetry in the brightness distribution of HH 204. We report for the first time a high blueshifted velocity (-118 km s-1) associated with HH 204 and show that the apex of HH 204 is indeed the zone of maximum velocity, in agreement with bow shock models. We also studied the radial velocity field of HH 269, finding features associated with the HH object. From our studies, we find kinematic evidence that suggests HH 203-204 and HH 202 are part of a big (~0.55 pc) bipolar HH outflow.